Apparatus for regulating the thickness of a coating on sheet material

ABSTRACT

A round-rod scraper is used to regulate the thickness of a coating on paper. The scraper is carried in a holder which is attached to one end of a pivotally mounted lever whose other end is carried by a bracket. The bracket also carries a tube filled with compressed air bearing against the lever through the intermediary of a plurality of independently displaceable pressure elements. The bracket itself is capable of having its position adjusted with the individual pressure elements held in fixed positions relative to one another.

United States Patent Nolden [54] APPARATUS FOR REGULATING THE THICKNESSOF A COATING ON SHEET MATERIAL [72] Inventor: Siegfried Nolden,Dusseldorf, Ger

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73 Assignee: Jagenberg-Werke AG Patentabteilung, Dusseldorf, Germany 7[22] Filed: Feb. 17, 1971 [21] Appl. No.: 115,950

[30] Foreign Application PriorityData Feb. 21, 1970 Germany".. ..P 20 08082.4

[52] US. Cl ..1l8/I26 [51] Int. Cl. 1l/02 [58] Field of Search.....l18/100, 126, 104; 117/64 R, 117/64 C, 102 A, 102 R, 102 M, 102 L, 102

[56] References Cited UNlTED STATES PATENTS 2,579,181 12/1951 Faeber..ll8/l26X 2,598,733 6/1952 Warner ..1l8/104 [451 Aug. 15, 1972 1 1/1954Montgomery et al..l 18/104 X 2,729,192 1] 1956 Warner ..-.1 18/465 X3,113,890 12/1963 Johnson eta] ..l18/l26 3,182,632 5/1965 Vazdikis ..118/104 3,187,718 6/1965 Coghill ..15/256.51 X

FOREIGN PATENTS OR APPLICATIONS 1,064,729 4/ 1967 Great Britain 1 18/126Primary Examiner-:Morris Kaplan Attorney-Burgess, Dinklage & Sprung [57]ABSTRACT A round-rod scraper is used to regulate the thickness of acoating on paper. The scraper is carried in av holder which is attachedto one end of a pivotally mounted lever whose other end is carried by abracket. The bracket also carries a tube filled with compressed airbearing against the lever through the intermediary of a plurality ofindependently displaceable pressure elements. The bracket itself iscapable of having its position adjusted with the individual pressureelements held in fixed positions relative to one another.

3 Claim, 2 Drawing Figures APPARATUS FOR REGULATING THE THICKNESS OF ACOATING ON SHEET MATERIAL The invention relates to a device forregulating the coating thickness in the coating of continuous webs ofsheet material such as paper, plastic or the like, by means of a roundscraper bearing on the coated side of the web. Specifically, theinvention relates to the design and principle of operation of theelements holding and actuating the round-rod scraper.

The coating of continuous webs of paper is generally done by applyingthe coating medium, disposed in a storage container, to the moving paperweb by means of dipping, transfer and/or coating rolls, with the paperweb initially receiving some excess of coating medium. Downstream of thecoating device, in the direction of travel of the paper web, a round-rodscraper is disposed which extends across the entire width of the paperweb and bears against the coated side of the paper web, its functionbeing to hold back the excess coating medium received by the web, thecoating thickness being determined by the magnitude of the bearingpressure. The round-rod scraper further serves to bring about theuniform distribution and leveling of the coating medium remaining on theweb.

Such round-rod scrapers, which can be driven at any desired speed and inany desired direction of rotation, as dictated by the nature of thesubstrate material and of the coating medium and by the particularoperating conditions, offer the advantage over conventional doctorblades equipped with fixed spreader knives that they avoid the formationof stripes on the coated side of the web which may be caused by fibersor other foreign bodies which may become lodged there.

Securing a uniform and adjustable bearing pressure for the round-rodscraper poses aproblem, however, and this bearing pressure is the factorwhich determines the uniformity and quality of the coating. It istherefore very important that the round-rod scraper be made to bear,with respect to its longitudinal extension, with the desired pressuredistribution within the various zones against the paper web supported bya roll. The prior-art mounting and bearing-pressure systems forround-rod scrapers fall short of being the perfect solution to thisproblem because they fail to provide the requisite elasticity for aperfectly uniform pressure distribution.

It is accordingly an object of the invention to provide a mounting andbearing-pressure system for a round rod scraper which offers assurancethat the elasticity of the mounting and loading means for theround rodprovides a maximum of adaptability.

This and other objects and advantages are realized in accordance withthe present invention wherein the round rod scraper is carried in aholder which is pivotally mounted on an adjustable bracket. The holderis acted upon by a distensible organ carrying a pressure medium andlikewise supported by said bracket, said distensible organ being actedupon by a plurality of pressure elements which are adjustable in knownmanner independently of one another relative to the direction of theround rod scraper. The arrangement is such that the holder receiving theround rod is fastened to the free end of one or more levers whosefulcrum is supported by the bracket.

Preferably, the holder has a C-shaped mouth smaller than the diameter ofthe round rod and is formed of an elastic or resiliently deformablematerial such as plastic or the like, whereby said round rod scraper canbe pushed into and removed from said mouth of said ing outward. Withinthe range of said counterroll, a

round rod scraper 3 comes to bear against the coated side of the paperweb 1. Depending on the nature of the coating medium, the round rodscraper 3 may be pro vided with a smooth or contoured surface. A drive(not shown) rotates the round rod scraper 3 preferably in the directionopposite to that of the paper web 1. A prism-shaped holder 4,constructed of an elastic or resiliently displaceable'material such asplastic or the like, is provided with a C-shaped mouth or notchS whichpartially surrounds the round rod scraper 3, a cleaning felt 6 whichextends over the entire length of the round rod scraper 3 being embeddedin said notch. 1

The separation of the lips forming the mouth 5 is somewhat smaller thanthe diameterof the round rod scraper 3, and this adequately secures theround rod scraper 3 in position while readily permitting it to beinserted and. removed by virtue of the elasticity of the material of theholder.

The holder 4 receiving the round rod scraper is fastened to the free endof one or more levers 7 whose fulcrum 8 is supported by a bracket 9. Inthe upper part of said bracket 9, at the level of the holder 4, there isdisposed a hose or tube 10, made of rubber or the like, to whichcompressed air is adjustably admitted and which bears against the upperend of lever 7, and hence the holder 4 carrying the round rod scraper 3.The hose 10 is mounted in known manner in a plurality of pres sureelements 11 which are disposed side by side over the length of the roundrod scraper and which are guided in a slide bar 17 connected with thebracket 9. The elements I 1 can be displaced independently of oneanother by means of spindles l2 and handwheels 13 via the interposedflange bolts 18. Y

The precision adjustment of the round rod scraper 3 in the direction ofthe paper web I. is achieved by rotating the spindle 12. For example, ifthe handwheel 1 3 and spindle I2 rotate in clockwise direction theyadvance to the left as seen in FIG. 1 and carry flange bolt 18 to theleft. In turn, this moves the element 11 to the left in the slide bar17. Locally this compresses the tube 10 slightly for the desired effecton holder 4 and round rod scraper 3 at the selected location. All ofthis is achieved against the action of coiled spring 20 which undergoescompression as the cap 21 of spindle 12 bears against the head 22 offlange bolt 18.

To release the pressure at a pre-determined location along round rodscraper 3, the handwheel 13 is rotated in counterclockwise direction.Under the influence of spring 20 the head 22 of bolt 18 moves to theright in FIG. 1 (in downward direction as viewed in FIG. 2) whichresults in movement of element 11 in the same direction.

In addition, the common bracket 9, to which both the round rod scraper 3and the hose are indirectly fastened, is also constructed so as to beadjustable and fixable in position, so that regardless of the setting ofthe individual elements the device can be advanced and retracted as aunit by known means, such as the stationary spindle 23 and the guide 24.Moreover, the angular position of the body 9 can be varied around thefulcrum 25 and secured by means of the clamping screw 26.

In this fashion the pressure at individual locations along the round rodmay be adjusted either to render uniform all pressures, and thusthicknesses of coating, or to render them non-uniform in predeterminedfashion.

It will be appreciated that the instant specification and examples areset forth by way of illustration and not limitation, and that variousmodifications and changes may be made without departing from the spiritand scope of the present invention.

What is claimed is:

1. In an apparatus for regulating the thickness of a coating on a web ofsheet material comprising a roll about which said web moves and around-rod scraper extending transversely of said web against said rolland operating on the coating, the improvement which comprises a holderfor said scraper, a lever carrying said holder and being pivotallymounted about a fulcrum parallel to said scraper so that the bearing ofsaid scraper against said web may be varied, means for varying thebearing at spaced locations along said scraper, comprising a pressuredisplaceable member extending parallel to said holder, and a pluralityof pressure elements independently displaceable perpendicularly to saidholder to adjust the pressure longitudinally along said scraper throughthe intermediary of said displaceable member and said holder, saidpressure displaceable i member comprising a distensible tube positionedbetween said lever and said independently displaceable pressure elementsso as to transmit the action of said elements to predetermined locationsalong said scraper, and said holder being provided with a C- shapedopening for receiving said scraper, the mouth of said C being slightlysmaller than the diameter of said scraper, said opening beingresiliently deformable so as

1. In an apparatus for regulating the thickness of a coating on a web ofsheet material comprising a roll about which said web moves and around-rod scraper extending transversely of said web against said rolland operating on the coating, the improvement which comprises a holderfor said scraper, a lever carrying said holder and being pivotallymounted about a fulcrum parallel to said scraper so that the bearing ofsaid scraper against said web may be varied, means for varying thebearing at spaced locations along said scraper, comprising a pressuredisplaceable member extending parallel to said holder, and a pluralityof pressure elements independently displaceable perpendicularly to saidholder to adjust the pressure longitudinally along said scraper throughthe intermediary of said displaceable member and said holder, saidpressure displaceable member comprising a distensible tube positionedbetween said lever and said independently displaceable pressure elementsso as to transmit the action of said elements to predetermined locationsalong said scraper, and said holder being provided with a C-shapedopening for receiving said scraper, the mouth of said C being slightlysmaller than the diameter of said scraper, said opening beingresiliently deformable so as to permit said scraper to be pushed intoand removed from said opening.
 2. An apparatus according to claim 1,including a bracket carrying said lever at a location spaced from saidholder, said bracket also carrying said pressure displaceable member andsaid independently displaceable pressure elements.
 3. An apparatusaccording to claim 2, including means for adjusting the position of saidbracket and the elements supported thereby relative to said roll.